A little bit of improvements for fasta2nexus.py
A little bit of improvements for fasta2nexus.py

Nothing essential, just few improvements for better readability.
naumenko-sa/bioscripts,naumenko-sa/bioscripts,naumenko-sa/bioscripts,naumenko-sa/bioscripts,naumenko-sa/bioscripts,naumenko-sa/bioscripts